For the purpose of configuring a silicon (Si) semiconductor device, such as an integrated circuit (IC), or an electronic device, such as a liquid crystal display (LCD), it is necessary to configure a wiring that is formed of a material having low resistance and high electroconductivity. The configuration of a silicon large-scale integration (VLSI) necessitates a fine wiring technology for the purpose of enhancing the degree of integration. Recently, for the wiring for use in the silicon VLSI and the LCD, copper (Cu) that has lower resistance and higher migration resistance than aluminum alloy is preferably used (refer to Patent Document 1 shown below).
Patent Document 1: JP-A HEI 5-47760
Since the copper that forms the wiring is diffused in a neighboring insulating film, it is necessary to form a layer, such as of tantalum (Ta) or a nitride thereof (TaN), as a barrier layer serving to suppress this diffusion of Cu (refer to Patent Document 2 shown below).
Patent Document 2: JP-A 2001-44156
On the other hand, in the semiconductor device, such as a large-scale integration (LSI), the increase of the degree of integration requires the wiring to decrease its width. The decrease of the width of the wiring, however, entails such problems as increasing the ratio of the thickness of the barrier layer of high resistance occupied in the width of the wiring and, when the barrier layer is disposed as disclosed in Patent Document 2, inevitably increasing the effective resistance of the wiring.
Recently, unlike the conventional technique that forms a barrier layer of Ta or TaN, the technique that heats a film of Cu alloy, such as an alloy of Cu and manganese (Mn) (Cu—Mn-based alloy), deposited on an insulating film to self-matchingly form a barrier layer between a copper wiring and the insulating film has been disclosed (refer to Patent Document 3 shown below).
Patent Document 3: JP-A 2005-277390
The conventional barrier layer formed using a Cu alloy, however, has entailed the following problems.
(1) Since no sufficient barrier property against the diffusion of Cu from the wiring side can be secured, the Cu is diffused toward the insulating film side and the insulating film is prevented from securing the insulating property.
(2) Owing to the mutual diffusion, the Si on the insulating film side is diffused toward the wiring side and the resistance on the wiring side is inevitably increased.
(3) Owing to the deficiency in the adhesiveness between the barrier layer and the insulating film, the semiconductor device excelling in lasting reliability of operation cannot be configured.
The problems enumerated above are thought to be ascribable to the failure to make clear the configuration of a barrier layer that enables enhancing the adhesion with an insulating film and as well bringing about a sufficient barrier property against the diffusion of Cu and Si.